1. Field of the Invention
The present invention relates to an optical scanning device and an image forming apparatus. For example, the invention can be applied to plural-drum type printers and copy machines and the like.
2. Description of the Related Art
In an optical scanning device applied to an image forming apparatus such as plural-drum type color copy machines and color printers, as described in Japanese Patent Laid-Open, No. 11-194285, a plurality of beams for each of color components emitted from each of light sources have their optical paths combined by a pre-deflection optical system to enter a polygon mirror. The beam deflected by the polygon mirror passes through an fθ lens which constitutes a post-deflection optical system and then is separated into the beam for each of color components to be irradiated to a drum for each of color components.
For example, it is assumed that a surface inclination is generated in a polygon mirror by a manufacturing error or an attaching error, causing optical performance degradation. Conventionally, performance degradation is improved by rotationally adjusting a cylindrical lens for each laser beam around the beam moving direction. However, this approach requires adjustment of the cylindrical lens by the number of laser beams (the number of color components) and therefore increases adjustment processes.
Although the above case is explained by taking a polygon mirror as an example, when performance degradation of other optical element components as common in a plurality of laser beams is improved, optical element components need to be adjusted by the number of laser beams (the number of color components), resulting in increased adjustment processes.